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Abstract
The thermodynamic properties of the dipolar hardsphere fluid are studied using theory and simulation. A new theory is derived using a convenient mathematical approximation for the Helmholtz free energy relative to that for the hardsphere fluid. The approximation is designed to give the correct lowdensity virial expansion. New theoretical and numerical results for the fourth virial coefficient are given. Predictions of thermodynamic functions for dipolar coupling constants lambda = 1 and 2 show excellent agreement with simulation results, even at the highest value of the particle volume fraction phi. For higher values of lambda, there are deviations at high volume fractions, but the correct lowdensity behavior is retained. The theory is compared critically against the established thermodynamic perturbation theory; it gives significant improvements at low densities and is more convenient in terms of the required numerics. Dipolar hard spheres provide a basic model for ferrofluids, and the theory is accurate for typical experimental parameters. lambda less than or similar to 2 and phi less than or similar to 0.1. This is demonstrated explicitly by fitting osmotic equations of state for real ferrofluids measured recently by analytical centrifugation.
Original language  English 

Article number  021126 
Pages (fromto)   
Number of pages  9 
Journal  Physical Review E 
Volume  86 
Issue number  2 
DOIs  
Publication status  Published  23 Aug 2012 
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Dive into the research topics of 'Thermodynamics of dipolar hard spheres with lowtointermediate coupling constants'. Together they form a unique fingerprint.Activities
 1 Research and Teaching at External Organisation

Ural Federal University
Philip Camp (Visitor)
2006 → 2012Activity: Visiting an external institution types › Research and Teaching at External Organisation